Personal alarm systems are systems that monitor vulnerable persons to detect certain situations or actions, such as possible falls, conspicuous behaviour or pressing an alarm button. They are widely used to allow vulnerable people (e.g. the elderly) to live safely in their homes or service flats for longer. Warnings are transmitted to a manned control room, which is expected to investigate the situation further and take any necessary action.
To be able to exclude false alarms and determine the specific help needed, a validation is carried out. This can be done by listening and voice interaction with the vulnerable person. In conventional systems classic telephone or VoIP lines are used for this purpose. These are used in case an actual alarm is detected or occurs at the location of the vulnerable persons. In other words, the personal alarm system establishes the call to the control room and the control room ends the call. In order to carry out a second call after a successful relief action, another procedure must be followed to call the control room from the location of the vulnerable person. In practice, this is done using a timer that automatically calls the control room again, e.g. 30 minutes after the event that triggered the alarm. This timer must be reset by manually pressing a specific button at the location of the person.
The purpose of the listening/voice interaction with the vulnerable person is to validate the alarm (and filter out false alarms) and to determine the specific needs and urgency of the call. It also reassures the person that effective assistance is on the way. The listening/voice interaction can be performed, for example, with a personal alarm device such as the Bosch CRS-H61-EU. This device is placed in a location in the person's house and is connected to the telephone line. Usually this is not near the place where the person has fallen or is in distress, with the result that the vulnerable person cannot effectively participate in the telephone call. Alternatively, a standard or mobile phone of the person can be used. This may be located at a place closer to the location of the fall but must be able to be picked up by the vulnerable person, because this call always leaves from the control room.
Wireless network systems, for example, wireless communication systems or wireless sensor systems, where a plurality of transmission units send data to one or more receiver units by means of wireless signals, are known in the prior art.
These network systems can occur in all kinds of configurations. Well-known examples include star networks, where each transmission unit communicates directly with a single receiver unit, often referred to in professional literature as a ‘central unit’, and mesh networks, where some of the transmission units also act as receivers and can forward signals.
A wireless network system is one of the possible implementations of the sensor network described in DE10 2014 100 642. This document describes a system consisting of a plurality of sensors for detecting acoustic and/or optical signals. The sensors have both loudspeaker and microphone functionality. A central unit, implemented as a central bus connected to a sensor bus, receives and processes the signals from the sensors. The central bus can be directly connected to sensors. Each ‘bus participant’ is connected to the sensor bus and thus to the sensors. The central bus and the bus participant comprise an actuator which is used for performing acoustic, optical or electrical signals.
By providing sensors through which audio communication can be effected, the above-mentioned problem—that the vulnerable person cannot access a telephone in case of emergency, for example due to a fall, to report the emergency situation—is resolved. The listening/speech function in the sensor thus increases the physical safety of the vulnerable person.
However, the solution disclosed in DE10 2014 100 642 has some important drawbacks. The proposed system consumes a lot of power because the sensors with microphone function are constantly on and because a lot of computationally-intensive tasks have to be carried out during processing to process the incoming sensor signals. It is stated that in some embodiments this processing can even partly be done in the sensors, because the amount of data that has to be transported over the bus is thus reduced.
Due to the statistical processing of the sensor signals, the received sensor signals (including the acoustic signals) must be transmitted time-synchronously to the central unit in the proposed system. It is emphasised that strict time-synchronicity of the microphone signals is crucial for the proper functioning of the system. It is clear that this can only be done at the expense of greater power consumption.
US2002/005894 discloses a system for detecting an event within a premises and for providing data such as live or recorded video, audio and data regarding that event to a website. The event may be an unauthorized entry to the premises, a fire or a maintenance malfunction within the premises. The website may be accessed by a variety of authorized users including the owner or manager of the premises, a central monitor, local police, fire or emergency medical personnel, or other entities specified by the owner or manager of the premises. The system permits authorized users to view the event in real time or as recorded on the website after the event has occurred to determine the type of event and an appropriate course of action to rectify it. In case an alarm situation is detected at the premises, a system controller in the premises is activated, which then opens a two-way combined data, audio and video channel to the website. Also a signal is transmitted locally to turn on a particular camera that covers the tripped detector. The document however remains silent on how a conversation between an individual at the premises and the central monitor is set up.
Consequently, there is a need for a power-efficient system in which one or more of the aforementioned disadvantages are avoided or solved and in which the privacy of the monitored person is always respected.